Nipah virus (NiV) and Hendra virus (HeV) are closely related viral zoonoses that form the genus Henipavirus in the family Paramyxoviridae. They are enveloped, negative-sense RNA viruses that cause a systemic and fatal disease in a variety of animal hosts and in humans. They are classified as biological safety level-4 (BSL4) viruses and possess several characteristics, such as the ability to be transmitted via aerosol that justifies their listing as Category C biothreat agents by the NIH and CDC. There is currently no approved therapeutics against either NiV or HeV and death is certain for approximately 75% of the cases. Ribavirin has been used against HeV and NiV with no effect. We have identified a fully human monoclonal antibody, m102.4, that potently neutralizes all available NiV and HeV isolates in vitro and provided post-exposure protection of ferrets from NiV challenge and of African Green Monkeys (AGM) from HeV challenge. We believe that m102.4 would, therefore, provide an effective post-exposure prophylactic against both NiV and HeV. Our objective here is to produce sufficient quantities to perform IND-supportive pharmacology, toxicology and efficacy studies as necessary steps in its preclinical development. We plan to pursue our objective through the following specific aims: 1) Develop analytical characterization methods for m102.4; 2) Manufacture m102.4; 3) Perform preclinical toxicology and pharmacokinetic studies; and 4) Determine the minimal protective dose and its therapeutic window in ferret and AGM challenge models. By the end of the funding period, we will have (i) prepared a characterized research-grade pre-seed for use to manufacture a m102.4 Master Cell Bank, (ii) optimized a development-scale process suitable for the manufacturing of cGMP clinical trial materials, (iii) manufactured more than 60 grams of development-grade m102.4 drug substance to perform IND supportive pharmacokinetic, toxicology, and efficacy studies, and (iv) executed said studies. Subsequent applications will pursue full cGMP manufacture of 1) a master cell bank and 2) antibody for Phase 1 clinical evaluation. Profectus BioSciences, Inc. has the necessary development and outsourcing expertise, experience and quality systems in place that will be needed to support these activities proposed under subsequent applications.